Wednesday, 8 October 2008

Sony NV-U50 G Sat Nav device

Some of you may be thinking that this blog has stopped being a computer forensics blog and is now only covering sat navs. It seems that way lately, but it is just that my computer cases are all run of the mill whilst sat navs are nearly always new and exiting!

The Sony NV-U50 G sat nav I looked at is running Sony Personal Navigation System version 1.06 software within Windows CE. It has 512mb of internal memory and no external flash media. I accessed it via Mobile Device Centre in Vista (probably Active Sync will suffice but I did not test with this) and discovered a My Flash Disk volume as normal. A folder named Sony will be accessible and within the NAV-U sub folder the following notable files can be found:
  • recent.txt
  • favourites.txt
  • prefs.ini
All three files are plain text.

prefs.ini is used to store user preferences but also contains three useful values:
  • hometarget
  • lasttarget
  • LastVisibleArea
hometarget contains the postcode and latitude and longtitude coordinates of the user set home location. lasttarget was not populated on the device I examined but I understand from colleagues that it can contain the last navigated to location. Both these values comprise of seventeen fields separated by the pipe symbol (|).

contains the lat/long coordinates of the bottom left and top right corners of the last map displayed on the device prior to being switched off. I had seen that the manual for the device contained the note:
The Sony Personal Navigation System always opens with the screen that was active at the time you switched off the device.

recent.txt and favourite.txt contained recently navigated to locations and user stored favourite destinations respectively. Each location record comprised of seventeen fields separated by the pipe symbol (|) in both files allowing them to be imported into an excel spreadsheet using the text data import wizard.

Example of a single favourite record.
GFRIEND|-|48|12366|-|-|SW1 1AA|-|-|-|-|-0.142076|51.50107|-|-|-|-|
Field 3
in most cases contained the value 48 which I understand to be the Country Code used by Sony/Navteq for the UK, Field 4 had in some cases a five digit number beginning with the digits 12. I speculate that these fields have something to do with the RDS/TMC facility available with this device. Fields 12 and 13 contained the Longtitude and Latitude coordinates of the location record (stored in decimal notation). Fields 16 and 17 if populated contained a second set of Longtitude and Latitude coordinates which I can only speculate may be journey origins.

The device can also store pre-planned itineraries and these are stored within files with a .rte file extension in the Sony/NAV-U/Routes folder. These files are plain text formatted the same way as recent.txt and favourite.txt .

By carrying out a live examination of the device most the data above can be ascertained, however where a user has allocated a name to a favourite or itinerary only the allocated name will be displayed - not the underlying address and lat/long coordinates.

UPDATED 17th December 2008

I have been asked whether the order of the entries in Recent.txt had any significance. I have carried out some further testing and established:

i) Recent.txt will contain a maximum of thirty entries.

ii) If the entry is generated by a user choosing to navigate to a Favourite via the Favourites menu button the display name will be stored along with other location information within Recent.txt.

iii) The most recently entered location is recorded last.

iv) Once there are thirty entries within Recent.txt when a new location is added the oldest record at the top of the list is deleted. An exception to this is if a new location duplicates an entry already stored in Recent.txt the older entry is deleted (wherever it was stored in the list) and a new location appended to the end of the list.

I also had another look at the secondary lat/long values and I am now of the view that they DO NOT contain journey origins. During testing all the values I was able to populate in these fields were fairly near to the location chosen to navigate to. I could not however discern their relevance.

1 comment:

Anonymous said...

Not been able to test this yet but as the second co-ordinate pair often points to a nearby population centre, is it possibly a point of origin for compiling a shortlist of nearby points of interest? Just an idea.